What does a ac high pressure hose look like - 2001 Buick Century

It is in the inlet of the AC compressure high pressure hose to the evaporator on most models, if it not there it is part of the high pressure hose assembly.

Their are two (2) lines coming out of the back side of the pump, one of them will have a hose type clamp on it and be a bit big around than the other, that one is NOT the high pressure line. it is the return line.

YOU NEED A R-134 GAUGE SET TO CHECK LOW PRESSURE SIDE AND HIGH PRESSURE SIDE.YOU ALSO CAN BUY A LITTLE CHEAPER GAUGE TO CHECK YOUR AC LOW BLUE SIDE AND HIGH RED SIDE AT ANY AUTO ZONE OR ADVANCE AUTO PARTS.WHAT YOU DO WHEN YOU GET YOUR GAUGE SET HOOK GAUGE TO LOW PRESSURE SIDE BLUE CAP PORT AND GAUGE TO HIGH SIDE PRESSURE RED CAP PORT.YOU CRANK CAR UP GET IT OPERATING TEMPERATURE.THEN TURN AC ON HIGH COOL LET RUN 3 TO 4 MINUTES.CHECK LOW SIDE GAUGE READING SHOULD BE 28 - 32 PSI. HIGH PRESSURE SIDE GAUGE SHOULD 199 - 228 PSI. THATS NORMAL CHARGE. SEE YOU CANT JUST RECHARGE AC SYSTEM UNTIL YOU CHECK IT FIRST YOU WILL DAMAGE SYSTEM .NOW YOU CAN GO TO AUTO ZONE PARTS BUY A CHARGE CAN WITH GAUGE AND HOSE.ATTACH TO IT.YOU NEED MORE THAN ONE CAN.WARNING MAKE COMPRESSOR IS RUNNING WHEN YOU TURN ON AC .BECAUSE IF COMPRESSOR NOT RUNNING CHECK FUSE AND AC COMPRESSOR RELAY.IF BOTH OKAY.YOU COULD HAVE OPEN CLUTCH COIL A FAULTY LOW PRESSURE SWITCH WILL CAUSE AC NOT TO WORK. IF LOW PRESSURE GAUGE BLUE SIDE PRESSURE IS 28 OR 30 YOU DONT NEED A CHARGE.PROBLEM SOME WHERE ELSE.BE SURE TO WEAR SAFETY GLASSES WHEN WORKING ON AC SYSTEM.

Check fuses, also if you can or have some one help you check for freon pressure, that will also disable the a/c compr. Go to a small indepened repair shop they will do this check for much less.

Obviously a high pressure ac hose but you mean high side or low side? Sorry I don't know.

1st you must check for correct refrigerant levels in ac system, must be done with a/c guages, you have a pressure switch that senses correct pressure in a/c system if you are low in refrigerant the a/c will not come on. if you have good pressures high side 70-95 low side 70-95 depends on ouitside air temperature, with the engine off then look at the switch in the high pressure line, jeep also has a fuse in the fuse box under the hood and a a/c relay please check those too. I hope this helps. (red is high side hose- small fitting plug , blue is low side- larger fitting If ac is working and compressor is on good pressure ranges from high side the red hose 160 to 230 depending on temperature outside; low side blue hose 27-46 low side depending on outside temperature, Wear glasses to protect your eyes. I hope this helps good luck

I’m happy to help further over the phone at https://www.6ya.com/expert/gregory_8e6ba270263743ac

Do you have ac gauges?You can only check with set of 134a gauges.Hook the red hose of the ac gauges to the large ac port on the high side ac line(it is the small ac line/hose).Do not turn the red knob on (on the ac gauges)If need to hook up low side(blue hose)to the small ac port on the low side line(it is the large ac port).If I can help,let me know.

To diagnose problems, an A/C manifold gauge set is needed to read high and low side pressure readings. Avoid adding refrigerant with a simple charging kit like the ones sold at parts stores. Don’t add any stop leak, this can cause problems in the compressor, expansion valve or condenser.
Keep in mind that using an A/C gauge set and seeing BOTH high and low side readings can help in diagnosing the problem when you know what to look for. First, on a 134A system the high and low side service ports are different sizes. AC gauge sets have color coded hoses, the blue color coded hose has a connection that fits on the low side service port and the red hose has a connection that will only fit onto the high side. The yellow hose won’t hook up to anything if just checking the readings; it can be used to connect to a vacuum pump or attached to a refrigerant can or tank.

Normal readings on high and low side with AC OFF (static pressure) - Depends on outside temperature, but normally is between 80-105 PSI
Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s - Ranges from 25-35 PSI - Note that on many Chrysler products a normal reading on the low side may be 15-25 PSI
Normal high side reading ranges from 200-350 PSI

Don’t assume that if adding little Freon is good that adding a lot is better!  Overcharging just a little can decrease the performance of the system and possibly damage the compressor.

Both low and high side readings are lower than normal, this indicates a cars AC system is low on refrigerant and is under-charged.
If both low and high side readings are too high, this indicates an overcharged system - too much refrigerant. This also can indicate that the condenser fan is not working, is too slow or the car is overheating and heat is transferring from the radiator to the condenser.

Good luck and hope this helps, keep me posted be glad to answer any question you may have. And yes the A/C system on your car uses R143a and there is a A/C pressure switch along the low pressure line or on the accumulator, it looks like a oil pressure sensor with a two wire lead cliped on it. 

The big pipe is the low pressure side. mark with S

there are 2 ports one for low pressure and one for high pressure. the low pressure is bigger in diameter and is usually close to the dryer and or fender and firewall. the high pressure is near the condensor on the fron of the vehicle. if there are caps for the ports low will be blue and high will be red. low side pressure should be 35-50 psi and high pressure should be 135-150 psi